MRI is a method of imaging internal information of a subject body using a NMR (Nuclear Magnetic Resonance) phenomenon. A complex image having a size and an angle of a rotating magnetization vector is obtained as an MR image. In the past, a magnitude image, obtained by imaging only magnitude of an MR signal, has been used as the MR image. However, since unevenness of a magnetic field has been adequately reduced due to recent progress of MRI technology, a phase image obtained by imaging a rotational angle of a magnetization vector is now available. Along with this, for example, a phase image is used in addition to the magnitude image, so that an SWI (Susceptibility Weighted Imaging) image, enhanced in phase difference by using change in susceptibility, may be provided in practice, as in patent document 1. This has drastically improved image contrast or resolution.